In a projection type video display, the usual geometrical raster distortions associated with a cathode ray tube display may be exacerbated by the use of a curved face plate CRT and the inherent magnification in the optical projection path. The use of a curved face plate CRT may offer benefits in a reduction of projection path length, and may also enable optical imaging simplification. However, the tube deflection may require the generation of specially shaped, highly stable, correction waveforms in order to achieve more stringent convergence requirements imposed by large screen viewing.